Beta alkoxy crotonic acid esters in froth flotation processes



BETA ALKOXY CROTONIC ACID ESTERS IN FROTH FLOTATION PROCESSES Roger F. Powell, Gwelo, Southern Rhodesia, and Eric F.

Martin, Germiston, Transvaal, Union of South Africa;

said Powell assignor to National Chemical Products Limited, Germiston, Transvaal, Union of South Africa No Drawing. Original application June 13, 1950, Serial No. 167,912, now Patent No. 2,687,214, dated August 24, 1954; Divided and this application August 2, 1954, Serial No. 447,442 a Claims priority, application Great Britain June 14, 1949 2 Claims. (Cl. 209-466) The present application is a division of our depending application Serial No. 167,912, filed June 13, 1950, and which'has since matured as U. S. Pat. No. 2,687,214, granted Aug. 24, 1954.

This invention relates to froth flotation processes for the concentration of noble and base metal'ores, of coal and of non-metallic ores, in which processes froths are produced by adding frothing agents to the flotation pulp in the same manner and for the same purpose as steam distilled pine oil is used.

The froth flotation agents of the present invention are particularly adapted for the treatment of pyritic ores, gold ores containing small amounts of'sulfides or arsenides, the bulk treatment of copper ores containing siliceous gangue, the treatment of ores in which two or more base metals are to be separated from each other, such as copper, lead, zinc or the like and cyanide slime plant residues of the type where recovery by flotation has presented great difficulties using the methods hereto available. The present frothers are likewise suitable for use with ores containing tarnished pyrite, chalcocite, and ores of the complex lead-Zinc type.

The beta alkoxy crotonic acid esters of this invention are typified by the structural formula An object of the invention is to provide improved froth, flotation agents for the flotation of mineral pulp, the

improvement particularly marked with respect to:

(l) A lesser amount of frothing agent required per unit quantity of ore being treated.

(2) A higher rate of dispersibility of the frother in an aqueous pulp;

(3) A higher carrying or collecting power as this is understood in the art;

(4) A greater selectivity of the frother in its action ice between the desired mineral products and the gangue, and

(5) A greater persistence of the frother in 'recirculation to provide for high recovery and minimum floating of the gangue.

A further'object of the invention is to provide a methed for concentrating minerals by flotation, comprising adding to the mineral pulp a small quantity of a beta alkoxy crotonic acid ester, the alkoxy groups being connected to an alpha carbon of a methyl or ethyl ketone by a CO-C ether linkage, said alkoxy being selected from the group consisting of" methoxy, ethoxy, normal propoxy, isopropoxy, methoxy-ethoxy and-ethoxy-ethoxy and thereafter subjecting the resulting mixture to a flotation. operation.

Other and further objects of the present invention will. appear from the more detailed description set forth be-- low, it being understood that such detaileddescription is.

given by way of illustration and explanation only and not by way of limitation, since various changes therein may be made by those skilled in the art without departing;

from the scope and spirt of the present invention.

The beta alkoxy crotonic acid. esters may be prepared.

through the Williamson synthesis from the correspond-- ing chloro crotonic acids or esters.

standardised flotation tests are carried out in a 2000-- gram Denver'Fahrenwald fixed-speed flotation machine:

without the addition of any. air other than that sucked in: in the normal manner. Different gold chalcopyrit'e. pyrrhotite ores, from different mines were blended and tested: in each, the valuable minerals to be floated were chalcopyrite and pyrrhotite, the latter only being auriferous. The ores differed in the percentages of these minerals present, in their natural pH after grinding, and in the amount of deleterious colloidal material present. The ore assayed;l6.8 dwts. as gold.

2000 grams of moist ore were ground for 45 minutes in a ballmill with 1200 cubic centimeters of tapwater, 4 grams of lime and 0.10 gram of copper-sulphate. The pulp was washed out and made up to standard volume in a 2000-grarn Denver-Fahrenwald flotation machine.

0.10 gram of sodium-secbutyl xanthate was then added to the pulp plus one drop from a standardised capillary tube, of the substance being tested as frother (each drop found by measurement to be approximately 0.0135 cc.). After 30 seconds the suction-air valve was opened, and a primary concentrate collected for exactly one hundred and twenty seconds. Suction-air valve was closed and another 0.25 gram of the xanthate added, plus 4 standardised capillary drops of the frother. Suction-air valvewas opened, and froths allowed to run over the lip of the machine for 5 minutes, with a standard stream of water being meanwhile added to the pulp at the back of the machine. This constitutes the secondary concentrates. Suction-air valve was then closed, bottom plug was opened, and the tailings (residue) pulp) washed out into a bucket. Primary concentrates, secondary concentrates, and tailings (residue) were filtered, dried at C., and analyzed.

The pH of the tailings pulp was found to be approximately 9.2, the pulp being well-flocculated and the degree of grinding being approximately 62% minus 200- mesh.

.Average figures are given in Table I below, and a comparison is made with a control test using 111:3 triethoxybutane commercial whose properties have been estab lished as superior to steam-distilled pine oil on several large well-known ore concentrators for several years.

TABLE I Standardized, comparative flotation tests in a 2,003 gram Denver-Fahrcmmld machine Products, Percent Weight A ssoys of Products Units 01' Sulphur (Percent X assay) Material Percent, Sulphur Dwt.

1st Cons. 2nd Cons. Tailings Tailings Gold 1st Cons. 2nd Cons. Tailings Cal. Ore

Tailings 1st Cons. 2nd Cons.

11l13 'llicthoxy butane com- 7. 03 6. 32 7.3 3i). (-5 82 0. Sb 5. 0 215. 5 146. 9 74. G 437. 0

mcrcial (Control). Ethyl beta etlloxy crotonate ii. 92 6. 37 S0. 71 27. 05 20. 60 0. 80 4. 75 187. 2 131. 2 69. O 387. 4

Percentage of Total Sulphur Quantity of Substance added Material Remarks 1st Cons. 2nd Cons. 'lailingrs 1st (3021., 2nd Coir, Tot/.11, cc.

co. co.

1:1:3 Triethoxy butane com- 49. 3 33. 6 17. l .028 .042 070 Control test. Froth a little watery, but active.

inereiel (Control). Persistent. Ethyl beta cthnxy crotonate. 4S. 3 33. 9 17. 8 03) 0'15 075 Just liquid at room temperature. Conditioning time about as for Pine Oi]. Very strong, deep, active froths. Verypersistent.

What is claimed is:

1. A method for concentrating minerals by flotation, comprising adding to the mineral pulp a small quantity of a beta alkoxy substituted crotonic acd ester, having the formula.

CH3C=CCX where X is alkoxy selected from the group consisting of methoxy, ethoxy, isopropoxy, inethoxy-ethoxy and ethoxy-ethoxy and Y is doubled bonded oxygen, the alkoXy References Cited in the file of this patent UNITED STATES PATENTS 1,902,070 Halbig Mar. 2l, 1933 2,561,251 Van Aardt July 17, 1951 2,591,289 Powell et al. Apr. 1, 1952 

1. A METHOD FOR CONCENTRATING MINERALS BY FLOTATION, COMPRISING ADDING TO THE MINERAL PULP S SMALL QUANTITY OF A BETA ALKOXY SUBSTITUTED CROTONIC ACID ESTER, HAVING THE FORMULA 